Semantic?
Killian Jones and Emma Swan have earned from the show creators, therefore it is canon, two titles: Kindred Spirits and True Love. These two emblems define their relationship. Now, I have read on my dash people debating about the Soul Mate category. This is just my opinion but, if we think about semantics, kindred spirits and soul mates seem to refer to, practically, a similar type of deep connection. Technically, one seems to be related to the spirit, the other to the soul. The challenge becomes, then, to establish a comparison between spirit and soul. This is a subtle task and I don’t think the writers of Ouat go so deep in their narrative, it is not their usual, actually they are known as mixers of symbols, tales, legends and mythologies, they make a full salad with them.
The discussion I saw came out because of Killian 2.0, the Wish version of Killian 1.0. Considering that both are equally real and share the exact same story up to the point where Wish Regina did not cast the first dark curse, would Killian 2.0 be allowed to find his True Love? His Soul Mate? His Kindred Spirit?
For me, the answer is yes, and I do believe that her name is Emma (maybe not Swan, because of a divergent story in the Wish Realm, but she is the daughter of Wish Snow and Wish David (who, unfortunately, have passed away thanks to Regina). I believe that she is his deepest connection of soul and spirit, she is his true love, the same way as he is hers.
I insist that the best solution for the Wish Mess, under a narrative perspective, to fix its major plot holes would be if there was a Wish Emma, somehow trapped somewhere, maybe in an object carried by Wish Hook (could be the rook) and because of that she would be, now, also cursed in HH. Maybe trapped in that Fremont Troll to where Rogers, Alice and Weaver use to go - maybe she is the Guardian!! (dreaming too much, I know). If the Wish Emma plot could become true, though, there could be another small problem, but easily sorted out by tracing for her a parallel with the paths’ divergence, similarly to the paths for Killian 2.0 and Killian 1.0. Wish Emma is not Emma Swan, but Killian 2.0 is not Killian 1.0. The Wish version of Captain Swan could still be Kindred Spirits (or Soul Mates) and True Love.
Wish Emma is a dream of mine, a wish that, unfortunately, I don’t believe will become canon.